A USB drive mounted via the command line or Dolphin will not unmount
so long as either Dolphin is running or the terminal is using anything
on the USB drive as its working directory (i.e.. #pwd) Dolphin
generate's a HAL error message saying essentially that the device is
busy. Likewise when using the umount command in the terminal, it
reports the USB device as busy.
However, if you terminate Dolphin and then restart it, you can
right-click on the USB disk icon in "Places" and unmount or eject
without problem.
Therefore, perhaps Dolphin could be tweaked to allow the unmount
without having to leave the program and come back to it.
Ian Robinson
Salem, Ohio